Steatite-type body and method of producing same



Patented Au 14, 1945 UNITED STATES PATENT OFFICE f STE ATITE-TYPE BODY AND METHOD PRODUCING SAME Henry L. Crowley, South'Orange, and Arthur M. Hossenlopp, Metuchen, N. .L, assignors to Henry L. Crowley & Company, Inc, West N. 1., a corporation or Newiersey No Drawing. Application May 11, 1944,

, Serial No. 536,020

4 Claims. (Cl. 106-46) 'Ihis invention relates to steatiteceramic bodies, the type methods of preparing them;

One of the objects 01' this invention is to provide a new form of fired ceramic body having improved mechanical and electrical characteris- 4 tics and particularly having Q values inexcess of s runner object of this invention is the provision of a new stcatite-type or ceramic body vitritied at relatively low temperatures as, for examwithin the range of 1250 C. down to as low as 900' C mixtures comprising them and the a further object of the invention is to shorten the firing time even at the lower temperatures noted above. 4

Other Objects and advantages or this invention will be apparent from the following description.

This invention resides substantially in the products, s ps, and series or steps, all as will be hereinafter set forth in full detail.

ordinarysteatltebodies arefixedon an8to 16 hour cycle although such bodies can be satisfactorilyfiredin from 8'to 9 hours as a preferred Such bodies are so fired for these time periods at a temperature 0! from 1250' C. to 1400' C. 1

It is an object or this invention to provide a ceramic body prepared irom amixture or suitebb ingredients whichwill be capable of being fired to vitrification at a temperature or from 1260' C. down to as low as 900C. in aperlod of about one hour, thereby resulting in a considerable economy because of the reduced firing time and heat requirements.

Asuitabiemixtureinaccordancewiththisin vention comprisu the following ingredients in Ball clay is a material comprising essentially alinninum oxide (A1209 and silicon dioxide (SiOi) in approximately equal proportions. Talc isalsoawellknownmaterialhavingthe chemical composition of oxide (M80) 80% by weight and silicon dioxide with the remainder principally water. This productislowinlimecontent.

Suitable mixtures of the above ingredients in v he proportion ranges disclosed will produce bodies having the approximate chemical proportions by weight:

A130! 4.52 to 4.79 3&0 21.35 to 33.00 CaO 3.85 to 4.08 1 0.64 to 6.83 MgO 21.15am i122 5104 47.40 $028.00 2110 1.141 12.12

Mixtures of these various ingredients within the proportion ranges listed above are prepared. to which mixtures are preferably added suitable organic binders and the like well known in the art. These mixtures are then formed into pieces 0! the desired shape by extrusion, compression and the like'and then fired for periods of one hour or less at the preferred temperatures ranging from 1100 C. down to 950 C; until complete vitrification results, although satisfactory results have been obtained at temperatures ransing from 1250 C. to 900 0. 'As those skilled in the, art

willunderstand,'tliefirlngtimesandtemperatures will vary with the ingredient proportions to quencies thus very well adapting them produce the final desired result. Bodies thus prepared have very high Q factors as, for example,inoneinstaneeaboiwthuspreparedhada Q factor of 6800'which is very high whencompared with-Q factors 0'! 1000 to 1500101 high grade steatite bodies now extensively manufactured for commercial purp seswhen deslredttmsebodiesmaybeimmted withwaxorotherwaterproofingcompoundsoas torenderthemimpetvioustomoistureandthus insure stabilization of their electrical characteristics under various atmospheric conditions. It ha alsobeenioundthatbodiesthusprepared.

have very low electrlcal'losses at very high ireto many modernelectricalusea.

From the above description, it will be apparent tothoseskilledintheartthatthesubiectmatter or this invention is subject to variation within the limits specified and we-do not, therefore.

desiretobelimitedexceptasrequiredwthelndi 0 60% by weisht.

. Barium carbonatiiBaCOa) 24to85 Zinc oxide1(zn0 1 to 10 1o Boric acid {H3303 1 w 10 Talc 58 29 2. Insulating bodies having a composition of incated acope of the invention and the appended CaO 335104.08 claims.- BeO: 0.841108.

What is claimed is: MgO 21.15 to 11.22 1. Insulating bodies having a composition of 810: 47.40 to 28.00 ingredients in parts by weight comprising: 6 ZnO 1.14 to 12.12 Ball clay 1 3. A method of preparing a-ceramic insulating Whiting (CaCCb-Calcium carbonate)--- 6 body comprising firing the mixtures of claim 1 for a period of not more than one hour at a temperature bqtweenl250 C. and 900 C.

4. A method of preparinga ceramic insulating ture between 1250 C. and 900 C.

HENRY L. CROWLEY. 

